Insect Repellent

Picaridin and natural insect repellents

Clinical tests all conclude that insect repellents using DEET (N, N-diethyl-3-methylbenzamide) as their active ingredient are effective. However, DEET has an off-putting smell and doesn't feel good on the skin. DEET is also a solvent for which improper use is risky, and in higher concentrations, it can ruin clothing, plastic and paint finishes. Therefore, many question whether DEET is the safest thing to put on your skin. Some researchers and pediatricians warn that even using DEET according to the label instructions may pose health risks. Noting an association with seizure incidents among children, the Environmental Protection Agency (EPA) categorizes DEET as "slightly risky."

While DEET has been around for decades, scientists did not know exactly how it worked. A recent study by researchers at Rockefeller University, however, helped to discover that DEET blocks the odors that attract insects to humans. The importance of this discovery is significant both in understanding the chemical and in fueling further research. Now that scientists know how the chemical affects insects, they will be able to develop better and more effective alternatives to DEET.

Some alternative insect repellents smell and feel better then DEET; they cause less damage and are more pleasant to use, but no alternative to DEET has been shown to be as effective, especially against mosquitoes.

Although more alternatives are available, research consistently points to three insect-repelling ingredients as effective alternatives to DEET. The main drawback to these insect repellents is that you may need to reapply them more often, and each ingredient has advantages and drawbacks.

DEET: Chemical that's effective against mosquitoes, some flies, gnats and ticks. Safety is well-studied, but controversial. It works well for most people, but has a bad smell, and doesn't feel great on the skin. It can damage plastics, paint and synthetic fabrics, and should be washed off after use.

Picaridin: Synthetic; effective against mosquitoes, but not gnats. Doesn't harm clothing or plastic and is safe for kids over two months old. Protects for about 2.5 hours and is odorless. Works better for some people than others.

Lemon eucalyptus oil: Natural insect repellent, but can't be used by kids under three years old. Protects against mosquitoes, gnats and ticks. Lasts from four to eight hours. Doesn't damage plastic or fabric, but can stain leather. Some people don't like the smell, and it's more effective for some people than others.

Geranium/soybean oil: Natural mosquito repellent, safe for kids as young as two months. Doesn't damage clothing or plastics, but isn't as effective as DEET, lemon eucalyptus oil or picaridin. Not everyone likes the smell, it can feel sticky, and herbal insect repellents do not work as well for some people as others.

One of the main advantages of insect repellents that use picaridin is that they don't smell bad, and they also feel better on the skin. Unlike DEET, picaridin-based mosquito repellent doesn't need to be washed off your skin when you return indoors, and it doesn't damage plastics or synthetic fabrics. Experts consider it safe for kids, pregnant women and even for babies at least two months old.

The World Health Organization recommends picaridin as the best mosquito repellent against malaria, since it's less apt to irritate skin than DEET. As with DEET, the length of time a picaridin insect repellent protects completely against bites depends on its concentration. Picaridin is derived from a pepper, and though it doesn't usually irritate the skin, it can cause eye irritation. The review at Slate magazine reports that it actually attracts gnats rather than repels them. The relatively low concentrations available in the United States don't protect as long as 25 to 35% DEET insect repellents, so for longer exposures you have to apply it more often.

Although picaridin insect repellents available in other countries use higher concentrations, only low-concentration products are available at present in the United States. Cutter Advanced Sport (*est. $6.50, 6 oz.) has 15% picaridin, but it is only to be applied once a day. More reviews recommend the 7% picaridin version, Cutter Advanced (*est. $6 for 6 oz.) , which may be applied up to three times a day, making it a more versatile mosquito repellent. We found no reviews of OFF! FamilyCare Insect Repellent II Clean Feel (*est. $5 for 6 oz.), which contains just 5% picaridin.

Some tests show that only the 15% picaridin Cutter Advanced Sport protects against the most aggressive Aedes mosquitoes (found mostly in the tropics, but in some parts of the southern United States as well). Both versions of Cutter Advanced are effective against Culex mosquitoes, the type that can carry West Nile Virus. Since the manufacturer recommends applying Cutter Advanced Sport mosquito repellent only once a day, while the 7% picaridin Cutter Advanced insect repellent may be applied up to three times, the 7% is a more versatile choice.

For stronger, longer-lasting protection, Repel Lemon Eucalyptus (*est. $7.50 for 4 oz.) is a botanical (plant-based), natural insect repellent suitable for adults and children at least three years old. Repel Lemon Eucalyptus is a pump spray with 30% lemon eucalyptus oil plus a little alcohol (less than 10%); the other ingredients are unspecified.

The main advantage of Repel Lemon Eucalyptus over picaridin insect repellents is that it repels gnats as well as ticks and mosquitoes, and since it's available in the United States in higher concentrations, it offers longer protection per application. Protection time averages about as long as a 25% DEET mosquito repellent -- four to eight hours, depending on the species of mosquito. However, comparison reviews show that protection time varies more among individuals than with DEET, which pretty much works for everyone. Although lemon eucalyptus oil does not damage plastics, paint finish or synthetic fabrics the way DEET does, it can stain leather. Most, but not all reviewers like the fragrance of Repel Lemon Eucalyptus, although it doesn't feel as clean on the skin as picaridin; some say it has a tacky feel.

No health problems have been associated with lemon eucalyptus oil, and the Centers for Disease Control recommend it for protection against mosquito-borne diseases. Like any insect repellent (natural or otherwise), it should first be tested on a small area of skin to make sure it doesn't cause an allergic reaction.

For children as well as adults, Canadian health authorities recommend soybean-oil natural insect repellents like Bite Blocker (*est. $9 for 4 oz.) , which is also recommended by the American Pediatrics Academy. Bite Blocker is the most recommended natural insect repellent, because it uses only food-grade, renewable, plant-based ingredients. Although soybean oil itself has some ability to repel insects, Bite Blocker adds quite a few other ingredients to enhance its effectiveness, including vanillin and geranium oil. In comparison tests, Bite Blocker's proprietary mix consistently outperforms other natural insect repellents, except for Repel Lemon Eucalyptus. However, as with Repel, Bite Blocker is more effective for some people than others.

Reviews say Bite Blocker natural mosquito repellent is approximately as effective as a 7% DEET repellent against ticks and Culex mosquitoes -- about 90 minutes to two hours -- but is safe to reapply. Tests against more aggressive Aedes mosquitoes give mixed results. One review shows no protection, while the USDA test against four different species shows Bite Blocker protects as long as Repel Lemon Eucalyptus. The informal review at Slate magazine notes that while Bite Blocker feels cool when applied, it also feels sticky (not surprising, since it's oil-based), and it stings on cuts. (Most reviews warn against applying any insect repellent over cuts.)

DEET insect repellents

Is DEET safe?

While it's clear that DEET damages certain materials, its effects on human health aren't as easy to judge. Studies of DEET's effects on rats show that it's a neurotoxin that damages brain cells and decreases mental and motor abilities, but these effects have not been proven in humans. There are a few cases of children dying, contracting encephalitis or having seizures, apparently linked to exposure to DEET. Animal testing has also shown an increase in the chemical's toxicity while using Panretin, a topical drug for certain AIDS-related skin lesions. On the other hand, DEET has been used and studied for about 60 years -- tested and studied more than any other insect repellent -- and judged relatively safe when used according to directions.

Canadian health authorities have stricter limits on insect repellents than do the corresponding agencies in the United States. So while the U.S. Center for Disease Control (CDC) says DEET is safe in high concentrations of up to 98%, even for children (but not babies under two months of age), Health Canada is limiting DEET concentrations to 30% and advising parents not to use any DEET on babies till they're at least six months old.

Pediatricians in Canada disagree with one another as much as pediatricians in the United States do. One is quoted as saying that for every report of toxic effects caused by DEET, another 19 cases go unreported. Another says he'd use DEET on his own children as fast as they sweated it off, despite Health Canada's advisory. In the United States, a professor at Duke University warns that DEET can become much more toxic when a person is also exposed to other chemicals or is simply under stress -- and that children are especially vulnerable.

Both the CDC and the EPA have declared, however, that DEET is safe for most people when used according to directions. To use DEET insect repellent safely, label instructions say to use it only on exposed skin, never under clothing. When you come back indoors, you're supposed to wash it off your skin and change any clothes to which you've applied it. This is inconvenient, and experts estimate that many users don't follow these guidelines.

All in all, whether or not DEET is safe to use is one of those issues that each user (and parent) will have to decide based on personal risk assessment. Even Health Canada advises using higher concentrations of DEET when traveling into parts of the world where mosquitoes carry malaria or dengue fever. If there are outbreaks of West Nile virus or encephalitis in your area -- diseases that just one mosquito bite can carry -- the known danger of the diseases can easily outweigh doubts about the safety of DEET. On the other hand, the World Health Organization (WHO) recommends picaridin even for malaria-ridden areas, so that's another alternative.

Best DEET mosquito repellents

Reviews note that you can minimize the possible health risks of DEET exposure by using a controlled-release DEET insect repellent. These products encapsulate DEET in a polymer so it doesn't penetrate the skin as much; instead, the DEET stays on the surface where its vapors can repel insects. While reviews testing controlled-release insect repellents find that they don't actually extend the protection time against bites, experts do confirm that these products serve to minimize exposure to DEET.

3M Ultrathon is recommended in more reviews than Sawyer Family Controlled Release (*est. $8 for 6 oz.), but comparison tests show that both insect repellents are quite effective. Sawyer Family Controlled Release lotion has 20% encapsulated DEET, while 3M Ultrathon comes in three versions with different encapsulated DEET concentrations. The strongest, 3M Ultrathon 12 Lotion (*est. $10 for 2 oz.) , is 34% DEET. This exceeds guidelines from Health Canada, the authority equivalent to our EPA, which recommends limiting DEET concentrations to 30%.

The American Pediatrics Academy also recommends a limit of 30% for children (and for babies as young as two months), though the EPA says higher concentrations should be just as safe for kids. Since the polymer base that encapsulates the DEET minimizes skin absorption, the extra 4% DEET in the Ultrathon 12 Lotion is probably not a significant issue. However, 3M Ultrathon 8 (*est. $9 for 6 oz.) comes in an aerosol spray with 25% DEET and in a pump spray (*est. $8 for 6oz.) with 19% DEET, if you prefer a lower concentration. According to the various health agencies, these concentrations minimize risks, but still give you three to five hours of protection. One drawback is that formulas using encapsulated DEET are more expensive.

As noted above, reviews agree that insect repellents using DEET are consistently effective, and comparison tests show less variation in effective protection time among individuals for DEET than for other insect repellents. Therefore, if the odor and skin feel don't bother you much -- and they bother some people much more than others -- then a standard DEET insect repellent is a cost-effective choice. Reviews say the brand doesn't matter unless you want to avoid certain inactive ingredients or preservatives; it's the percentage of DEET that makes one insect repellent protect for a longer time than another.

For a brief exposure of an hour or two, a low concentration of 5-10% should do the trick. OFF! FamilyCare Unscented IV (*est. $5 for 6 oz.), formerly called OFF! Skintastic IV, has 7% DEET, as does Cutter Skinsations (*est. $5 for 6 oz.) . Note that while using an insect repellent with such a small percentage minimizes exposure to DEET, most of the product is alcohol (ethanol), which is a solvent with some documented health risks of its own. OFF! FamilyCare Insect Repellent IV Light & Fresh Towelettes (*est. $5.50 for a box of 12) contain alcohol, but also contain aloe vera, though no reviews were available for these. We found several user-written reviews praising DEET insect repellents that use water as a carrier instead of alcohol. Ben's Tick and Insect Repellent, Wilderness Formula 30 (*est. $6 for 4 oz.) also comes in wipes (*est. $5 for 12 wipes) and in a wide range of sizes down to a tiny 1.25-ounce pump spray (*est. $3), especially handy for hikers.

Ben's 30% DEET concentration is about the optimum amount reviews recommend for most people, with an average protection length of about five hours. The average duration of full protection goes up as DEET percentages increase, but after 50% the increase is minimal. Because of this, reviews suggest that even for long periods of exposure, it's best to use a product that has 25% to 35% DEET, then reapply as needed. If you prefer an alcohol base to water, a classic insect repellent is OFF! Deep Woods (*est. $6, 6 oz.) . While the formula has changed from 23.8% to 25% DEET since the last reviews, the change is minimal enough that it shouldn't have too much of an effect. If you like the OFF! Product line, they have also recently introduced OFF! FamilyCare Smooth & Dry Insect Repellent I (*est. $5.50 for a 4-ounce aerosol can), which contains 15% DEET, and is supposed to lack the greasiness often associated with DEET repellents. We saw no reviews that confirm this, however.

Experts note exceptions to the 30% recommendation. Protection time is drastically shortened -- often halved -- in high heat, humidity and by rain or sweat. We found reviews from some hikers who prefer insect repellents with 95% DEET, such as OFF! Deep Woods Sportsmen (*est. $5 for one ounce) or Ben's 100 (*est. $7 for a 1.25 ounce pump spray) . For most situations, however, reviews say these high concentrations make for unnecessary cost and exposure to DEET.

Other insect repellents

There are a number of alternative insect repellents, but we found far more clinical support for picaridin, lemon eucalyptus oil and soybean/geranium oil than other alternatives to DEET.

We found more than one review recommending Buzz Away Extreme natural insect repellent (*est. $8 for 4 oz.) , which uses a different blend of soybean and geranium oils than Bite Blocker, and Burt's Bees Herbal insect repellent (*est. $8 for 4 oz.) which uses lemongrass and citronella oil. In user reviews, some people report that the Burt's Bees mosquito repellent has an unpleasant oily feeling and others claimed that while it helped repel mosquitoes, it attracted other insects.

Although reviews say an active ingredient called IR3535 is reasonably effective as an insect repellent, it's easier to find in Europe. In the United States, Avon combines it with sunscreen in Avon Skin So Soft Bug Guard Plus IR3535 (*est. $6 for 4 oz. lotion) . But the EPA and other experts recommend using two separate products instead of one that combines sunscreen with insect repellent. One reason is that a University of Florida study shows that the repellent in combination products gets absorbed into the skin more than in plain insect repellent products. Since this Avon insect repellent uses IR3535 rather than DEET, that reasoning may not apply here. However, experts also say that sunscreen should be applied more often than insect repellent, in order to minimize exposure to the latter.

As noted earlier, it's possible to find positive reviews for just about every insect repellent on the market, even if comparison tests have shown that it's effective for very few people or for extremely short periods of time. Most research says that B vitamins don't make any difference in mosquito bites, but we found a review at About.com that tests and praises the effectiveness of the vitamin-B1 Don't Bug Me! Patch (*est. $16 for 20 36-hour patches). The least-recommended products are wrist and ankle bands, since they don't distribute their vapor over enough exposed skin. If you wear long pants, ankle bands might be effective against ticks, but they'll still leave your arms and face exposed to mosquitoes, gnats and flies.

Historically, various plants have been used in different parts of the world as insect repellents. You can find recipes online for making your own insect repellent from one or more plant oils -- see our Best Research section below. Neem oil looks promising, while catnip oil gets contradictory results in research studies. But comparison tests that include botanical insect repellents show that while some work well for some people, it's impossible to predict before trying one whether or not it will prove worth the money. (Lemon eucalyptus oil and Bite Blocker are the best plant-based bets for most people.) And just because a product is plant-based doesn't make it safe -- think of poison ivy and deadly nightshade.

In fact, botanical repellents are as apt to cause allergic reactions as any other insect repellent. For example, Health Canada is phasing out the use of both citronella and oil of lavender, because of established health risks. Experts say it's especially important to avoid plant oils that are apt to be "sensitizers," meaning that they may cause a heightened allergic reaction to many other substances as well. This is how "chemically sensitive" people become allergic to ingredients that caused them no problems earlier.

Important Features: Insect repellent

Experts offer the following tips for using insect repellents:

• Test any new insect repellent on a small area of skin first. The inside of the elbow is a good testing spot. Anyone can prove allergic to an ingredient, so test first.

• Read and follow all directions on the product label. Apply sparingly, especially on young children. If the repellent doesn't damage fabric, apply it to the outside of clothing where possible, rather than directly to skin.

• Do not apply over cuts, wounds or irritated skin -- or near eyes and mouths of young children. Do not spray in enclosed areas. Do not use under clothing.

• Use separate insect repellent and sunscreen products. A 2004 study conducted by University of Florida researchers determined that using DEET combined with sunscreen could increase skin absorption. If you need both sun protection and insect repellent, reviews say you should apply sunscreen first, wait for it to dry, then apply insect repellent.

• In general, insect repellents aren't recommended for children under two months of age. Health Canada recommends waiting until kids are six months old. Protect babies with mosquito netting. Oil of lemon eucalyptus isn't recommended for children under age three. Pregnant and nursing women should consult physicians before using insect repellents.

• Be proactive at preventing mosquitoes from laying their eggs. Keep the yard and house free of containers filled with standing water. Stay indoors when most mosquitoes are active, beginning at dusk and throughout the evening. Wear light-colored, loose-fitting clothing that covers as much skin as possible.

• Wash DEET-treated skin with soap and water after returning indoors. Remove and wash treated clothing. (If you've sprayed clothing with a permethrin repellent, you can store it in plastic bags to keep it potent longer.)

Our Consensus Report shows how many times products are top-ranked by reviewers included in our
All The Reviews Reviewed chart.

# of Picks	Model (with Retailer Links)	Details from Amazon.com
8	Bite Blocker (soybean oil/geranium oil) (*est. $9 for 4 oz.)	details
8	Repel Lemon Eucalyptus (*est. $7.50 for 4 oz.)	details
6	3M Ultrathon (34% DEET) (*est. $10 for 2 oz.)	details
6	OFF! Deep Woods (25% DEET) (*est. $6, 6 oz.)	details
5	Cutter Advanced (7% picaridin) (*est. $6 for 6 oz.)	details
5	OFF! Skintastic (7% DEET) (now OFF! FamilyCare IV) (*est. $5, 6 oz.)	details
4	OFF! Botanical (Discontinued)	-
3	Cutter Advanced Sport (15% picaridin) (*est. $6.50, 6 oz.)	details
3	Sawyer 20% controlled release (*est. $8, 6 oz.)	-
3	Buzz Away Extreme (*est. $8 for 4 oz.)	details
2	Burt's Bees Herbal (*est. $8 for 4 oz.)	details
1 each	Autan, Avon Skin So Soft , Avon Skin So Soft Bug Guard plus IR3535 with sunblock , Ben's 30 , Ben's 100 Maxi-DEET , BugBand , Bug Off! Adult Biting Insect Repelling Wrist Band , Burt's Bees Lemongrass Insect Lotion, Buzz Off clothing, catnip oil , citronella , Don't Bug Me! Patch, OFF! Deep Woods for Sportsmen IV, Off Skintastic Magicolor (disc.), Cutter 10% spray , Cutter Unscented Outdoorsman , OFF! Deep Woods for Sportsmen I , Sawyer Broad Spectrum, Sawyer MAXI-DEET , Travel Medicine FiteBite

Reviews say lemon eucalyptus oil offers the longest-lasting protection from bug bites, but it's not to be used on kids under three years old. Bite Blocker, picaridin or DEET are considered safe even for babies as young as two months (though some experts say six months is safer). The most recommended DEET insect repellent is the 34% Ultrathon controlled-release version used by the U.S. military, followed by DEET-based products with even lower concentrations.

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